The present invention relates to a method of and apparatus for transferring heat within diverse user environments, using centrifugal forces to realize the evaporator and condenser functions required in a vapor-compression type heat transfer cycle.
For more than a century, man has used various techniques for transferring heat between spaced apart locations for both heating and cooling purposes. One major heat transfer technique is based on the reversible adiabatic heat transfer cycle. In essence, this cycle is based on the well known principle, in which energy, in the form of heat, can be carried from one location at a first temperature, to another location at a second temperature. This process can be achieved by using the heat energy to change the state of matter of a carrier fluid, such as a refrigerant, from one state to another state in order to absorb the heat energy at the first location, and to release the absorbed heat energy at the second location by transforming the state of the carrier fluid back to its original state. By using the reversible heat transfer cycle, it is possible to construct various types of machines for both heating and/or cooling functions.
Most conventional air conditioning systems in commercial operation use the reversible heat transfer cycle, described above. In general, air conditioning systems transfer heat from one environment (i.e. an indoor room) to another environment (i.e. the outdoors) by cycholically transforming the state of a refrigerant (i.e. working fluid) while it is being circulated throughout the system. Typically, the state transformation of the refrigerant is carried out in accordance with a vapor-compression refrigeration cycle, which is an instance of the more generally known xe2x80x9creversible adiabatic heat transfer cyclexe2x80x9d.
According to the vapor-compression refrigeration cycle, the refrigerant in its saturated vapor state enters a compressor and undergoes a reversible adiabatic compression. The refrigerant then enters a condenser, wherein heat is liberated to its environment causing the refrigerant to transform into its saturated liquid state while being maintained at a substantially constant pressure. Leaving the condenser in its saturated liquid state, the refrigerant passes through a throttling (i.e. metering) device, wherein the refrigerant undergoes adiabatic throttling. Thereafter, the refrigerant enters the evaporator and absorbs heat from its environment, causing the refrigerant to transform into its vapor state while being maintained at a substantially constant pressure. Consequently, as a liquid or gas, such as air, is passed over the evaporator during the evaporation process, the air is cooled. In practice, the vapor-compression refrigeration cycle deviates from the ideal cycle described above due primarily to the pressure drops associated with refrigeration flow and heat transfer to or from the ambient surroundings.
A number of working fluids (i.e. refrigerants) can be used with the vapor-compression refrigeration cycle described above. Ammonia and sulfur dioxide were important refrigerants in the early days of vapor-compression refrigeration. In the contemporary period, azeotropic refrigerants, such as R-500 and R-502, are more commonly used. Halocarbon refrigerants originate from hydrocarbons and include ethane, propane, butane, methane, and others. While it is a common practice to blend together three or more halogenated hydrocarbon refrigerants such as R-22, R125, and R-290, near-azeotropic blend refrigerants suffer from temperature drift. Also, near azeotropic blend refrigerants are prone to fractionation, or chemical separation. Hydrocarbon based fluids containing hydrogen and carbon are generally flammable and therefore are poorly suited for use as refrigerants. While halogenated hydrocarbons are nonflammable, they do contain chlorine, fluorine, and bromine, and thus are hazardous to human health.
Presently, the main refrigerants in use are the halogenated hydrocarbons, e.g. dichlorodifluoromethane (CCL2F2), commonly known as R-12 refrigerant. Generally, there are three groups of useful hydrocarbon refrigerants: chlorofluorocarbons, (CFCs), hydrochlorofluorocarbons, (HCFCs), which are created by substituting some or all of the hydrogen with halogen in the base molecule. Hydrofluorocarbons, (HFCs), contain hydrogen, fluorine, and carbon. However, as a result of the Montreal Protocol, CFCs and HCFCs are being phased out over the coming decades in order to limit the production and release of CFC""s and other ozone depleting chemicals. The damage to ozone molecules (O3) comprising the Earth""s radiation-filtering ozone layer occurs when a chlorine atom attaches itself to the O3 molecule. Two oxygen atoms break away leaving two molecules. One molecule is oxygen (O2) and the other is chlorine monoxide molecule (CO). The chlorine monoxide is believed by scientists to displace the ozone normally occupying that space, and thus effectively depleting the ozone layer.
While great effort is being expended in developing new refrigerants for use with machines using the vapor-compression refrigeration cycle, such refrigerants are often unsuitable for conventional vapor-compression refrigeration units because of their incompatibility with existing lubricating additives, and the levels of toxicity which they often present. Consequently, existing vapor-compression refrigeration units are burdened with a number of disadvantages. Firstly, they require the use of a mechanical compressor which has a number of moving parts that can break down. Secondly, the working fluid must also contain oil to internally lubricate the compressor. Mineral oil has been used in refrigeration systems for many years, and alternative refrigerants like hydrofluorocarbons (HFC) require synthetic lubricants such as alkylbenzene and polyester. These use of such lubricants diminishes system efficiency. Thirdly, existing vapor-compression systems require seals to prevent the escape of harmful refrigerant vapors. These seals can harden and leak with time. Lastly, new requirements for refrigerant recovery increase the cost of a vapor-compression unit.
In 1976, Applicant disclosed a radically new type of refrigeration system in U.S. Pat. No. 3,948,061, now expired. This alternative refrigeration system design eliminated the use of a compressor in the conventional sense, and thus many of the problems associated therewith. As disclosed, this prior art system comprises a rotatable structure having a hollow shaft with a straight passage therethrough, and about which a closed fluid circuit is supported. The closed fluid circuit is realized as an assemblage of two spiral tubular assemblies, each consisting of first and second spiraled tube sections. The first and second spiraled tube sections have a different number of turns. A capillary tube, placed between the condenser and evaporator sections, functions as a throttling or metering device. When the rotatable structure is rotated in a clock-wise direction, one end of the tube assembly functions as a condenser, while the other end thereof functions as an evaporator. As disclosed, means are provided for directing separate streams of gas or liquid across the condenser and evaporator assemblies for effecting heat transfer operations with the ambient environment.
In principal, the refrigeration unit design disclosed in U.S. Pat. No. 3,948,061 provides numerous advantages over existing vapor-compression refrigeration units. However, hitherto successful realization of this design has been hindered by a number of problems. In particular, the use of the capillary tube and the hollow shaft passage create imbalances in the flow of refrigerant through the closed fluid flow circuit. When the rotor structure is rotated at particular speeds, there is a tendency for the refrigerant fluid to cease flowing therethrough, causing a disturbance in the refrigeration process. Also, when using this prior art centrifugal refrigeration design, it has been difficult to replicate the refrigeration effect with reliability, and thus commercial practice of this alternative refrigeration system and process has hitherto been unrealizable.
Thus, there exists a great need in the art for an improved centrifugal heat transfer engine, which avoids the shortcomings and drawbacks thereof, and allows for the widespread application of such an alternative heat transfer technology in diverse applications.
Accordingly, it is a primary object of the present invention to provide an improved method of and apparatus for transferring heat within diverse user environments using centrifugal forces to realize the evaporator and condenser functions required in a vapor-compression type heat transfer cycle, while avoiding the shortcomings and drawbacks of prior art apparatus and methodologies.
A further object of the present invention is to provide such apparatus in the form of a centrifugal heat transfer engine which, by eliminating the use of mechanical compressors, reduces the introduction of heat into the system by the internal moving parts of conventional motor driven compressors, and energy losses caused by refrigeration lubricants used to lubricate the moving parts thereof.
A further object of the present invention is to provide a centrifugal heat transfer engine that contains the refrigerant within a closed system in order to avoid leakage, yet being operable with a wide range of refrigerants.
A further object of the present invention is to provide a centrifugal heat transfer engine having a rotor structure with a closed, fluid circulating system that contributes to a dynamic balance of refrigerant flow.
A further object of the present invention is to provide a centrifugal heat transfer engine having a rotor structure embodying a fluid circulation system which, when rotated direction in a first direction, has a first portion that functions as a condenser and a second portion that functions as an evaporator to provide a refrigeration unit, and when the direction of the rotor structure is reversed, the first portion functions as an evaporator and the second portion functions as a condenser to provide a heating unit.
A further object of the present invention is to provide a centrifugal heat transfer engine that either condenses or evaporates a chemical refrigerant as it is passed through a plurality of helical passageways which are part of its rotor structure.
A further object of the present invention is to provide a centrifugal heat transfer engine which provides a simple apparatus for carrying out a refrigeration cycle without the necessity for compressors or other internal moving parts that introduce unnecessary heat into the refrigerant.
A further object of the present invention is to provide a centrifugal heat transfer engine which does not require refrigerant contamination with an internal lubricant, and thus permits the refrigerant to function at optimum heat transferring quality.
A further object of the present invention is to provide a centrifugal heat transfer engine having a temperature responsive torque-controlling system in order to maintain the angular velocity of the rotor structure within prespecified operating range, and thus maintain the flow of refrigerant through the fluid circulating system of the rotor structure.
A further object of the present invention is to provide such a centrifugal heat transfer engine with a rotatable structure containing the self-circulating fluid circuit having a bidirectional throttling device placed between the condenser section and the evaporator section of the fluid circuit.
A further object of the present invention is to provide such a bidirectional throttling device for controlling the flow rate of liquid refrigerant into the evaporization length of the evaporator section of the rotor structure, and the amount of pressure drop between the liquid pressurization length and the evaporization length during a range of axial velocities (RPM) of the rotor structure.
A further object of the present invention is to provide such a centrifugal heat transfer engine, in which the optimum axial velocity is arrived at and controlled by a torque controlling system responsive to temperature changes detected in the ambient air or liquid being treated using an array of temperature sensors.
A further object of the present invention is to provide such a centrifugal heat transfer engine with a spiral passage along the shaft of the rotor structure in order to cause vapor-compression as it draws the heavy refrigerant vapor from the evaporator to the condenser in both clockwise and counterclockwise directions of rotation.
A further object of the present invention is to provide such a centrifugal heat transfer engine with a rotor structure having heat transfer fins in order to enhance heat transfer between the circulating refrigerant and the ambient environment during the operation of the engine.
A further object of the present invention is to provide such a centrifugal heat transfer engine, in which the closed refrigerant flow circuit within the rotor structure is realized as spiraled tubing assembly having spiraled tubular condenser section and a tubular evaporator section which are both held in position by structural supports anchored to the shaft and connected to spiraled tubes.
A further object of the present invention is to provide such a centrifugal heat transfer engine, in which the rotor structure is constructed as a solid assembly and the closed refrigerant flow circuit, including its spiral return passageway along the axis of rotation, is formed therein.
Another object of the present invention is to provide a novel heat transfer engine which can be used to transfer heat within a building, home, automobile, tractor-trailer, aircraft, freight train, maritime vessel, or the like, order is to maintain one or more temperature control functions.
These and other objects of the present invention will become apparent hereinafter and in the Claims to Invention.
In general, the present invention provides a novel method and apparatus for transferring heat within diverse user environments, using centrifugal forces to realize the evaporator and condenser functions required in a vapor-compression type heat transfer cycle.
According to a first aspect of the present invention, the apparatus of the present invention is provided in the form of a reversible heat transfer engine. The heat transfer engine comprises a stator, port connectors, a heat exchanging rotor, torque generator, temperature selector, a plurality of temperature sensors, a fluid flow rate controller, and a system controller.
The stator housing has primary and secondary heat transfer chambers, and a thermal isolation barrier disposed therebetween. The primary and secondary heat transfer chambers each have inlet and outlet ports and a continuous passageway therebetween. A first port connector is provided for interconnecting a primary heat exchanging circuit to the heat ports of the primary heat transfer chamber, so as to permit a primary heat exchanging medium to flow through the primary heat exchanging circuit and the primary heat exchanging chamber during the operation of the heat transfer engine. A second port connector is provided for interconnecting a secondary heat exchanging circuit to the inlet and outlet ports of said secondary heat transfer chamber, so as to permit a secondary heat exchanging medium to flow through the secondary heat exchanging circuit and the secondary heat transfer chamber during the operation of the reversible heat transfer engine, while the primary and secondary heat exchanging circuits are in substantial thermal isolation of each other.
The heat exchanging rotor is rotatably supported within the stator housing about an axis of rotation and having a substantially symmetrical moment of inertia about the axis of rotation. The heat exchanging rotor has a primary heat exchanging end portion disposed within the primary heat transfer chamber, a secondary heat exchanging end portion disposed within the secondary heat transfer chamber, and an intermediate portion disposed between the primary and secondary heat exchanging end portions. The heat exchanging rotor contains a closed fluid circuit symmetrically arranged about the axis of rotation and has a return portion extending along the direction of the axis of rotation.
The primary heat exchanging end portion of the rotor is disposed in thermal communication with the primary heat exchanging circuit, and the secondary heat exchanging end portion of the rotor is disposed in thermal communication with the secondary heat exchanging circuit. The intermediate portion of the rotor is physically adjacent the thermal isolation barrier so as to present a substantially high thermal resistance to heat transfer between the primary and secondary heat exchanging chambers during operation of the heat transfer engine.
A predetermined amount of a heat carrying medium is contained within the closed fluid circuit of the heat exchanging rotor. The heat carrying medium is characterized by a predetermined heat of evaporation at which the heat carrying medium transforms from liquid phase to vapor phase, and a predetermined heat of condensation at which the heat carrying medium transforms from vapor phase to liquid phase. The direction of phase change of the heat carrying liquid is reversible.
The function of the torque generator is to impart torque to the heat exchanging rotor and cause the heat exchanging rotor to rotate about the axis of rotation. The function of the temperature selector is to select a temperature to be maintained along the primary heat exchanging circuit. The function of the temperature sensor is to measure the temperature of the primary heat exchanging medium flowing through the inlet and outlet ports of the primary heat exchanging chamber, and for measuring the temperature of the secondary heat exchanging medium flowing through the inlet and outlet ports of the primary heat exchanging chamber. The function of the fluid flow rate controller is to control the flow rate of the primary heat exchanging medium flowing through the primary heat exchanging chamber and the flow rate of the secondary heat exchanging medium flowing through the secondary heat exchanging chamber, in response to the sensed temperature of the heat exchanging medium at either the inlet or outlet port in either the primary or secondary heat exchanging chambers and to satisfy the temperature selector setting.
The function of the torque controller is to control the torque generating means in response to the sensed temperature of the heat exchanging medium at either the inlet or outlet port in either the primary or secondary heat exchanging chambers and the selected operating temperature setting.